This application claims the benefit of Japanese Patent Application Number 2003-430628 filed Dec. 25, 2003, the entirety of which is incorporated by reference.
1. Technical Field
The present invention relates to a method for controlling a parallel kinematic mechanism machine in which a plurality of struts driven by actuators can move an end effector connected thereto, and a control device whereby to embody this method.
2. Description of the Related Art
A method described in the Japanese Patent publication of unexamined application No. 2002-91568 has been known as a conventional method for controlling a parallel kinematic mechanism machine. This method is such that actuator commands corresponding to the length of each strut are corrected with high accuracy while taking the amount of elastic deformation of each joint into account even when the struts are connected to the end effector with universal joints consisting of a combination of joints having one degree of freedom in rotation. Moreover, this method is such that conversion of inverse kinematics is used to calculate commands for the length of each strut from the position and posture commands of the end effector and from kinematic parameters.
Specifically, the conversion of inverse kinematics is performed without load to obtain uncorrected commands of each actuator. Then angles of each joint are calculated, loads acting on the components of the joints are obtained from loads acting on each strut and others, and the amount of elastic deformation of each component is calculated from the loads obtained. On the basis of the amount, kinematic parameters are corrected. With the use of the corrected parameters the conversion of inverse kinematics is again performed to obtain corrected commands of each actuator.